The functional role of nerve growth factor (NGF) receptors on neural crest tumors, particularly melanoma tumors, will be investigated. The hypotheses to be tested are that NGF is a functionally significant mitogen for such tumor cells, and that aberrant expression of NGF receptors may enhance their proliferative capacity. The effects of NGF on proliferation of human melanoma cell lines in serum-free culture will be tested. Molecular clones of the human NGF receptor gene and cDNA will be employed as hybridization probes to seek NGF receptor gene amplification or rearrangement in melanoma tumor cell lines. Monoclonal antibodies to NGF receptor will be employed to examine whether altered NGF receptor proteins exist in melanoma cell lines. This will be accomplished using the antibodies to stain Western blots of electrophoretically separated proteins from melanoma cells. The applicability of monoclonal antibodies to NGF receptor as immunocytochemical reagents for clinical diagnosis of melanoma and malignant Schwannoma will be examined. The effect of NGF on expression of myc and fos genes in melanoma cell lines will be examined by hybridizing labeled myc and fos gene probes to Northern blots of mRNA isolated from melanoma cells after varying periods of exposure to NGF.